Answer:
B is the answer.
Explanation:
Given equations y + x = 5 and 5x + 5y = 25.
These equations have infinetely many solutions because they are equivalent.
This can be proven by the multiplicative property of equality and the commutative property of addition.
y + x = 5 → y × 5 + x × 5 = 5 × 5 [multiplicative property of equality] → 5y + 5x = 25 → [commutative property of addition] 5x + 5y = 25.